Q1. Select the correct statement. If there is neither friction nor air resistance and there is no external force, a rotating ball at the stable position (X0,Y0) will

A. keep rotating at the same position (X0,Y0). B. stop to rotate at the same position (X0,Y0). C. moveto another position (X1,Y1), keeping the rotation speed.

D. be none of the above.

Q2. Which law does NOT explain the behaviour of the ball mentioned in Q1?

A. Newtons first law (the law of inertia)

B. Newtons second law (F=ma)

C. Newtons third law (action and reaction)

D. Thelaw of energy conservation

Q3.When you play a tug war with two persons in each team, there is an angle theta between two pulling forces in the same team. Regardless of theta, each person has the same pulling force, F. Which value of theta would maximize the net pulling force in the same team?

A. theta=0 deg

B. theta=45 deg

C. theta=90 deg

D. theta=180 deg

For reference